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read-cache: clean up casting and byte decoding

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This patch does a clean up pass to minimize the casting required to work
with the memory mapped index (mmap).

It also makes the decoding of network byte order more consistent by using
get_be32() where possible.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ben Peart 2018-10-10 11:59:33 -04:00 committed by Junio C Hamano
parent 252d079cbd
commit 371ed0defa
1 changed files with 11 additions and 12 deletions
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23
read-cache.c
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@ -1650,7 +1650,7 @@ int verify_index_checksum;
/* Allow fsck to force verification of the cache entry order. */ /* Allow fsck to force verification of the cache entry order. */
int verify_ce_order; int verify_ce_order;
static int verify_hdr(struct cache_header *hdr, unsigned long size) static int verify_hdr(const struct cache_header *hdr, unsigned long size)
{ {
git_hash_ctx c; git_hash_ctx c;
unsigned char hash[GIT_MAX_RAWSZ]; unsigned char hash[GIT_MAX_RAWSZ];
@ -1674,7 +1674,7 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
} }
static int read_index_extension(struct index_state *istate, static int read_index_extension(struct index_state *istate,
const char *ext, void *data, unsigned long sz) const char *ext, const char *data, unsigned long sz)
{ {
switch (CACHE_EXT(ext)) { switch (CACHE_EXT(ext)) {
case CACHE_EXT_TREE: case CACHE_EXT_TREE:
@ -1889,8 +1889,8 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
int fd, i; int fd, i;
struct stat st; struct stat st;
unsigned long src_offset; unsigned long src_offset;
struct cache_header *hdr; const struct cache_header *hdr;
void *mmap; const char *mmap;
size_t mmap_size; size_t mmap_size;
const struct cache_entry *previous_ce = NULL; const struct cache_entry *previous_ce = NULL;
@ -1918,7 +1918,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
die_errno("unable to map index file"); die_errno("unable to map index file");
close(fd); close(fd);
hdr = mmap; hdr = (const struct cache_header *)mmap;
if (verify_hdr(hdr, mmap_size) < 0) if (verify_hdr(hdr, mmap_size) < 0)
goto unmap; goto unmap;
@ -1943,7 +1943,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
struct cache_entry *ce; struct cache_entry *ce;
unsigned long consumed; unsigned long consumed;
disk_ce = (struct ondisk_cache_entry *)((char *)mmap + src_offset); disk_ce = (struct ondisk_cache_entry *)(mmap + src_offset);
ce = create_from_disk(istate, disk_ce, &consumed, previous_ce); ce = create_from_disk(istate, disk_ce, &consumed, previous_ce);
set_index_entry(istate, i, ce); set_index_entry(istate, i, ce);
@ -1961,21 +1961,20 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
* in 4-byte network byte order. * in 4-byte network byte order.
*/ */
uint32_t extsize; uint32_t extsize;
memcpy(&extsize, (char *)mmap + src_offset + 4, 4); extsize = get_be32(mmap + src_offset + 4);
extsize = ntohl(extsize);
if (read_index_extension(istate, if (read_index_extension(istate,
(const char *) mmap + src_offset, mmap + src_offset,
(char *) mmap + src_offset + 8, mmap + src_offset + 8,
extsize) < 0) extsize) < 0)
goto unmap; goto unmap;
src_offset += 8; src_offset += 8;
src_offset += extsize; src_offset += extsize;
} }
munmap(mmap, mmap_size); munmap((void *)mmap, mmap_size);
return istate->cache_nr; return istate->cache_nr;
unmap: unmap:
munmap(mmap, mmap_size); munmap((void *)mmap, mmap_size);
die("index file corrupt"); die("index file corrupt");
} }